Hi all,
I've used LMR33620ADDAR buck converter in my project. TI Webench to design the circuit of that converter, but it doesn't work as expected. I'm not sure whether my layout is bad or some of the components are incorrect or both. When I disconnect U5, and apply 3.3V directly the MCU works and all the levels are correct. The U4 has an output of around 3V instead of 12V. I would appreciate if you could have a look at the pics.
BOM:

		Farnell
U4	LMR33620ADDA	3007263
C17	10uF	2211159
C18	220nF	2905327
C19	1uF	2522376
C22	100nF	2611911
C23, C24, C25, C27	22nF	2581029
C28	100uF	1539477
L2	22uH	1869771
R16, R17	100k	2826073
R18	9.09k	1160198
C32,C33	100uF	1539477
U5	LM1117MPX-3_3_NOPB	3122024

Based on Webench:

 

I use an LMR38010, which might be a close relative of the LMR33620. When it was happy it worked beautifully, but it was really picky about the decoupling of its power input. It needed 1uF right on the power pin, 25mm away wasn't good enough for it.
Your supply decoupling actually looks OK, but I can't see where all the grounds go.
Does it behave peculiarly in different ways as you vary the input voltage? That's what my LMR38010 did!

 

In a switching regulator every lead is an inductor and resistor, and so layout is a vital component of the design.

 

If this was hand soldered did the die attach pad get connected? It must be for proper operation.